The present invention relates generally to an airport runway lighting system substantially as disclosed in commonly assigned U.S. Pat. No. 4,951,046. More particularly, the present invention comprises an automated monitoring system for observing the condition of lamps in the runway lighting system. Still more particularly, the present invention monitors the status of failed lamps and determines when these lamps must be replaced to insure continuity of guidance along a particular runway.
Existing airport runways typically include a series of runway light fixtures secured along the centerline and/or sidelines of an airport runway. Each light fixture includes one or more lamps which provide illumination to aircraft. The fixtures secured along a length of runway each are coupled by means of a series current transformer to a single alternating current transmission line extending from a constant current regulator through an electrical vault beneath the runway. Typically, each constant current regulator connects to a single current transmission line. Each constant current regulator, in turn, connects to a vault computer.
The constant current regulator typically generates a current at one of five preselected amplitudes, including 2.8, 3.4, 4.1, 5.2, and 6.6 RMS amperes. A lighting control panel located in the airport control tower transmits commands to the vault computer which controls the amplitude of current generated by the current regulator. The lighting control panel thereby enables airport personnel in the control tower to select individually the intensity of runway light illumination for each runway.
The monitoring of the airfield lighting system is critical for safe operation. As is apparent to one skilled in the art, safe operation of a runway can be compromised if an excessive number of runway lamps malfunction, especially if adjacent lamps malfunction, thereby changing the configuration of the runway lighting system.
ICAO ANNEX 14 recommends that
In order to provide continuity of guidance . . . an unserviceable light should not be permitted adjacent to another unserviceable light . . .
Thus, it should be apparent to those skilled in the art that an automatic monitoring system for runway lights would be beneficial and would enhance the safety of a runway lighting system. Such a monitoring system, however, has not been implemented because adopting such a system would require that existing systems be retrofitted with additional transmission lines and monitoring equipment, thereby making implementation costs prohibitively expensive.